Portable electric tool



July lo, C' ROBB PORTABLE ELECTRIC TOOL k Filed Aug. l2, 1932 2 Sheets-Sheet l fwerzor JAMES C. Rose Irl" July 10, 1934 J. c. ROBE 1 965 669 PORTABLE ELECTRIC TOOL I :L1-ed 12 1 2 Shee t She@ t 2 liz. den 2.101'

JAMES C. ROBE,

Patented July 10, 1934 UNITED STATES PATENT OFFICE 11 Claims.

This invention relates generally to improvements in the construction and design of portable multi-purpose electric tools of the hand-operated type.

Among the principal objects of the present invention is to provide a portable electric tool which, while entirely conventional in external appearance, size and weight, is nevertheless of such character as to afford a far wider range of appllcation than has been possible heretofore with the ordinary tool.

`Another object of the invention is to provide a tool which is characterized in that it is composed of several unitary assemblies, one of which is the power unit which includes a constant speed motor. This power unit, which constitutes in effect the primary unitary assembly, is so designed as to adapt it for quick-detachable connection to one of several secondary unitary ass'emblies whereby to provide the necessary and proper tool speed, the choice of the secondary unit being dependent upon the nature and purpose of the ultimate attachment which it is desired to employ.

Still another object of the invention is to provide in a tool of the character described a power unit which is adapted for use in connection with vone or another of a variety of speed reduction units, thus dispensing with the necessity cf-providinga complete separate tool for each desired tool speed.

A still further object of the invention is to provide a quick-detachable and yet positive locking means for eilecting the desired connection between the primary or power unit and any one of a group of secondary or speed reduction units, each of the latter being of course equipped to receive thew ultimate tool attachment.

Inasmuch as the character of the ultimate tool attachment is dependent upon the nature of the' work to be performed, it will be understood that for each secondary or gear reduction unit there may be several different tool attachments which may be selectively employed` as conditions warrant. In order to positively secure the tool attachment in operative position, it is among the objects of this invention to provide each secondary unit with a locking mechanism which is not only simple and compact in construction and easy to manipulate but which is also absolutely positive in the character of its operation.

Other objects of the invention and advantages resulting therefrom will be apparent from the detailed description of the invention which follows.

'I'he invention consists substantially in the combination, construction, arrangement and relative location of parts, all as will appear more fully hereinafter, as shown in the accompanying drawings and as finally pointed out in the appended claims. 50

In the said accompanying drawings:-

Figure 1 is a side elevational view of the portable unit in assembled form;

Figure 2 is a longitudinal vertical cross-sectional view of the unit;

Figure 3 is an end elevational view of the attachment tool end of the unit;

'Figure 4 is a View showing the locking means in operative position for locking the attachment against removal from the unit;

Figure 5 is a View showing the power unit, the gear reduction unit and the attachment tool in separated relation; and

Figures 6, '7 and 8 are cross-sectional views taken respectively on the lines 6 6, "I--l and 'I5 8 8 of Figure 2.

Referring now more particularly to the drawings, it will be observed that the multi-purpose tool as constructed in accordance with the principles of the present invention essentially com- Sil' prises a primary unit l0 and a secondary unit l1, the latter being adapted to receive the ultimate attachment, such as l2, which it is the purpose of the'tool to operate. In Figure 5, the primary and secondary units lil and and. the attechment l2 are shown in separated relation, it being understood, of course, that these units are adaptW ed to be connected together provide a cornpact hand-operated portable tool of substantially conventional form, size and weight, such as ap- Q@ pears in Figure l.

The primary unit le constitutes the power unit of the tool and comprises a main housing or casing 13 having the conventional hand grip 14 within which latter is suitably mounted the 9E usual trigger-operated type of electric switch 15. Secured to the outer end of the casing 13 is an end plate 16 having an annular flange 17 and a centrally disposed bearing flange 1S. The annular flange .17 is preferably of an external diam- 100 eter equal to that of the casing 13 so that when the end plate 16 is secured to the casing the external surfaces of the casing 13 and of the annular flange 17 are substantially ilush with respect to each other. Provided in the motor cas- 105 ing 13 adjacent the handle end thereof and in axial alignment with the bearing flange 18 is a bearing sleeve 19 for accommodating one endr of the motor armature shaft 20. The opposite" end 2l of this shaft is journalled within the bearing 110 nange 18 formed in the end plate 16, the said end 21 of the armature shaft being provided with a square or other such multi-sided axially extendingr socket or recess 22. The motor frame 23 is preferably secured rigidly in position within the interior of the motor casing or housing 13 by means of the studs 24. The motor armature is designated generally by the reference numeral 25. The casing housing 13 is preferably provided with a plurality of circumferentially spaced apertures 25 to aiord proper ventilation for the motor housed thcrewithin and in addition. en air circulating fan 27 is keyed to the shaft 2O for rotation therewith substantially in the plane of the circumfercntially spaced apertures 26. This primary or power unit which has just been described is adapted for use in connection with any one of a number of different secondary units, only one or' which has been shown in the drawlZlgS.

The secondary unit, which has been generally designated by the reference numeral ll, is in eiect a gear reduction unit and when it is properly coupled to the power unit ultimate driving speed is obtained which is different from that of the armature shaft. Obviously, different attachments require to be operated at different speeds and by the proper selection of the secondary unit the required speed may be obtained without necessitating any change in the power unit. In other words, only one power unit is required for a number of secondary gear reduction units and inasmuch as the motor end of the usual portable tool is the most expensive part thereof it will be apparent that by providing a single power unit adapted for use in connection with any one of several different secondary or gear reduction units, a considerable saving is effected.

The secondary or gear reduction unit which has been shown in the drawings is illustrative of that type of unit which is adapted for use in connection with the power unit 10. Essentially, each secondary unit comprises a main casing 28 within the interior of which is mounted a suitable gear reduction train designated generally by the reference numeral 29. The rear end'of the secondary unit casing 28 is of enlarged form and terminates in an axially extending annular flange 30 which is adapted to telescopically engage over the axially extending flange 17 of the power unit heretofore described. Mounted within the enlarged annular flange 30 of the secondary unit l1 is an end plate 31, this end plate 31 being provided with a centrally disposed bearing sleeve 32 for a stub shaft 33. One end 34 of this stub shaft 33 projects beyond and eX- teriorly of the end plate 31 for accommodation within the axially extending recess or socket 33 formed in the end of the armature shaft 20. This freely projecting end 34 of the stub shaft 33 is squared or otherwise shaped to t snugly within the axially extending recess so as to provide a positive driving connection between the armature shaft and the said stub shaft.33.

Also mounted within the secondary unit 11 with the opposite ends thereof suitably journalled within the bail bearings 35 and 36 is a tubular shaft 37, the inner end of this tubular shaft being provided with a squared or other such multisided bore, as at 38. This tubular shaft 37 is provided at the inner end thereof with a gear 39 forming part of a train of reduction gears entrained with and adapted to be driven by a gear 40 fixed to and rotatable with the stub shaft 33. It will here be understood, of course, that by varying the character of the gear train between the stub shaft 33 and the tubular shaft 37. the speed of rotation of the latter may be changed as desired. This is accomplished by providing a number of different secondary or gear reduction units each having its own particular type of gear train and each being adapted for quick-detachable connection to the power unit without necessitating any change whatsoever in the latter. In the particular illustration shown the secondary or gear reduction unit is of the type adapted to drive at proper speed a drill chuck 4l. The proper speed of rotation of this drill chuck is between 1250 and 1500 R. M. whereas the armature shaft speed is in the neighborhood of 10,000 R. P. M. Should it be desired to employ an attachment other than the drill chuck el and the proper speed of rotation of which is, for example, 2500 R. P. M. the gear reduction unit shown in the drawings would be replaced by another gear reduction unit which would afford the desired tool speed of 2500 R. P. M.

The attachments or ultimate tools. such as the drill chuck 4l shown in the drawings, are in every case provided with a shank 42 which ls adapted to be projected into the tubular bore of the tubular shaft 37. The rear end of the shaft 42 is squared or otherwise shaped for snug accommodation within the correspondingly shaped bore 38 of the tubular shaft 37 so as to provide a positive driving connection between the shaft 37 and the shank 42 of the ultimate tool to be driven.

In order to prevent longitudinal displacement of the ultimate tool with respect to the tubular shaft 37, there is provided a special locking means which will now be described. As appears moet clearly in Figures 2 and 4, the shank 42 of the ultimate tool is provided with a circumferential groove 43 within which are adapted to be seated a pair of readily movable detents 44-44, these latter detents being respectively projected through diametrically opposite sides of the tubular shaft 37. These detents 44-44 are respectively provided with enlarged heads 45 which limit their inward movement. these heads being respectively engaged by leaf springs 46 secured to the exterior of the tubular shaft 37, the leaf springs serving to resiliently seat the detenta within the groove 43 of the tool shank 42. While these leaf springs are sufficient to provide at all times a resilient latching engagement between the tubular shaft 37 and the tool shank 42, they are not of sufficient strength nor do they exert sumcient pressure to prevent the ready removal of the shank 42 from the tubular shaft 37 when desired nor do they prevent the convenient insertion of the tool shank 42 into the said shaft.

In order to positively lock the detents 44-44 into position to prevent the removal of the shank 42 from the tubular shaft 37, the latter is provided with a slldably mounted sleeve 47 having an axially extending flange 48 which is in spaced relation with respect to the tubular shaft 37. This flange 48 is adapted to slide over the leaf springs 46 in such manner as to effectually preclude their outward movement. 'I'he coil springs 49 interposed between the sleeve 47 and the fixed abutment 50 carried by the tubular shaft 37 tends constantly to urge the collar 47 into the locking position shown more particularly in Figure 4, it being understood that when the collar 47 is in the position shown in said Figure 4 it becomes impossible to withdraw the tool 41.

In order to permit the ready withdrawal of the tool, a. readily accessible and operable means is provided for shifting the locking collar 47 into inoperative position. This means, which is designated generally by the reference numeral 51, consists essentially of a shaft 52 extending radially throughlthe wall of the secondary unit casing 28, the outer end of this shaft 52 being provided with an operating knob 53 the inner end thereof being provided with an eccentrically mounted disc 54, the peripheral surface of which engages springpressed locking collar 47. Upon rotating the knob 53 into the position shown in Figure 2, the eccentrically mounted disc 54 forces the collar 47 axially along the tubular shaft 37 and against the action of the coil spring 49 to release the leaf springs 46. On the other hand, when the knob 53 is rotated into the position shown in Figure 4, the collar 47, under the action of the coil spring 49, is shifted into embracing relation with respect to the leaf springs 46 and so prevent the latter from being sprung outwardly to release and permit the withdrawal of the tool 41.

As has been already stated, the primary or power unit 11 is constructed as a unitary assembly which is complete in itself and entirely independent of the secondary or gear reduction units, the latter being also constructed as unitary assemblies complete in and of themselves. The power unit and the particular secondary or gear reduction unit which may be selected for use with'the power un't of course must be connected together in such manner as to insure an absolutely positive connection therebetween. This connection is preferably effected in the manner now to be described. As appears most clearly in Figures 2 and 5, the axially extending flange 17 is provided with a plurality of exterforly arranged ribs 55, each of these ribs 55 being substantially elongated and arranged angularly with respect to the longitudinal axis of the unit. Each secondary or gear reduction unit is provided interiorly of the axially extending flange 30 thereof with a plurality of grooves or recesses 56, each of these grooves or recesses 56 being substantially elongated and angularly arranged to respectively accommodate the ribs 55 provided on the power unit 10. These ribs 55 and the grooves or recesses 56 are relatively so formed and arranged as to provide in effect a plurality of inter-engaging cam surfaces which operate to draw the units 10 and 11 into positive connection with each other, it being apparent that in order to effect this connection it is merely necessary to start the ribs 55 into their respective grooves 56 and then by relative-rotation of 'the units l0 and ll effect the complete seating of the ribs 55 within their respective grooves 56. In order to prevent accidental disconnection between the power unit l0 and the particular gear reduction unit l1 which may have been connected thereto, the power unit is provided with a spring-pressed detent 57 the end of which is adapted for projection through one of several circumferentiaily spaced apertures 58 provided in the flange 30 of the secondary unit. As appears most clearly in Figure 6, the spring-pressed detent 57 extends radially through the flange 17 of the end plate 16 of the power unit, the outer end of this spring-pressed detent being suitably rounded, as at 59, to facilitate its riding inside the grooved portion of the flange 30 of the secondary unit while the latter is being rotated into locked position with respect to the power unit flange 17. As the ribs 55 of the power unit are ilnally seated within the internal grooves 56 of the secondary unit, the spring-pressed detent 57 comes into registry with one or the other of the apertures 58 'provided in the flange 30 of the secondary unit and is immediately projected therethrough to prevent any further relative rotation between the power unit 10 and the secondary unit l1. In order to dis-engage the secondary unit from the power unit, it is merely necessary to depress the spring-pressed detent 57 sufficiently to permit the flange 30 of the secondary unit to ride freely thereover, the desired dis-engagement between these units being then effected simply by rotating either one of these units relatively to the other. If desired, one or more circular shims 60 of paper or the like may be interposed between the abutting surfaces of the power unit l0 and the gear reduction unit 11 in order to insure a very positive connection between these units of non-vibrating character, these shims serving to take up any play which may develop between the units so connected.

From the foregoing, it will be apparent that a tool has been provided wherein a single power unit is adapted for connection with one or the other of several different gear reduction units, each of these gear reduction units being equipped to receive one or the other of several different kinds of ultimate tools to be driven. The result is the provision of a portable multi-purpose hand-operated electric tool which is not only conventional in appearance, weight and size but which also provides for suchinterchangeability of parts as to constitute in effect a power unit of universal adaptability. It will be understood, of course, that the power unit may be built in various szes or power ranges and that the several gear reduction units selectively adapted for use with each such power unit may likewise be bult in various sizes or power ranges, thus insuring correct tool speed for each and. every attachment or ultimate tool which is intended to be operated.

Of course, it will be understood that the lnvention is susceptible of various changes and modifications from time to time without departing from the general principles or real spirit thereof and it is accordingly intended to claim the invention broadly as well as specifically as indicated by the appended claims.

What is claimed as new and useful iszl. In a portable electric tool of the character described, in combination, a primary power unit including a casing and a motor mounted therein, and a self-contained independently complete secondary gear reduction unit quick-detachably connected in operative relation to said power unit.

2. In a portable electric tool of the character described, a primary power unit including a main casing, an electric motor mounted Within said casing, a plate fitted within the opposite end of said casing and constituting a bearing for one end of the motor armature shaft, and means provided in said plate for attaching a gear reduction unit to said power unit, said means being operative to lock said units together in cooperative relation upon rotating one of said units relatively to the other.

3. In a portabe electric tool of the character` described, in combination, a primary power unit including a main casing, an electric motor mounted within said casing, the armature shaft of said motor being journalled within opposed bearings provided in said casing; a gear reduction unit adapted for quick-detachable assembly with said power unit, said gear reduction unit including a motor-speed shaft adapted for direct axial connection with the motor armature shaft of said power unit, a tubular shaft for receiving the shank of the ultimate tool or attachment and a series of entrained gears between said motor-speed shaft and said tubular shaft; and cooperative means on said power unit and said gear reduction unit for effecting their quick-detachable assembly and the direct connection between said motor-armature shaft of the power unit and said motor-speed shaft of said gear reduction unit.

fi. In a portable electric tool of the character described, a self-contained unitary power assembly comprising a casing, an end plate secured to and enclosing the opposite end of said casing, an electric motor mounted within said casing, the armature shaft of said motor being journalled within bearings respectively provided in said casing and end plate, and means provided in said end-plate for removably attaching a self-contained gear reduction unit in operative relation to said power assembly, said attaching means being effective upon rotating said gear reduction unit relatively to said power assembly.

5. In a portable electric tool of the character described, a self-contained unitary power assembly comprising a main casing having a switchequipped handle, an electric motor housed within said casing with the armature shaft suitably journalled therein, said assembly being quick-detachably connected to a self-contained independently complete gear reduction unit with one end of said motor armature shaft in direct driving connection with an axially alined shaft in said gear reduction unit.

6. In a portable electric tool of the character described, a self-contained unitary power assembly comprising a substantially cylindrical casing having an end plate enclosing the open end thereof', said end plate being apertured to provide a single bearing for one end of a motor shaft, a second bearing arranged adjacent the opposite 'end of said casing and in coaxial alinement with said first-mentioned bearing, and a motor housed within said casing, the opposite ends of the armature shaft of said motor being respectively journalled in said bearings, the end of the shaft which is journalled in said end plate being adapted for direct drive connection with the shaft of a self-contained independently complete gear reduction unit, said end plate being secured to said casing independently of said gear reduction unit.

7. In a portable electric tool of the character described, in combination, a primary self-contained unitary power assembly including a main casing having an enclosed fore end and a motor housed within said casing, said motor having a shaft projecting axially through said enclosed end of the casing; a self-contained unitary gear reduction assembly including a casing having an enclosed rear end, a driving shaft journalled within said gear assembly casing and projecting axially beyondthe rear end of said latter casing, a driven shaft laterally offset from said driving shaft for accommodating the attachment to be operated by the tool, and a gear train entrained between said driving and driven shafts; and means for simultaneously effecting the removable attachment of said gear reduction assembly to said power assembly and the coupling together of said motor and driving shafts aforesaid.

8. In combination, a primary power unit including a main casing and an electric motor housed therewithin, said power unit being adapted for removable connection with any one of a plurality of gear reduction units of different gear ratios, the power shaft of said motor being journalled within said casing; a gear reduction unit of a predeterminedly fixed gear ratio including gear-entrained driving and driven shafts; and means for simultaneously connecting together said power unit and gear reduction unit and coupling together the power shaft of the power unit and the driving shaft of the gear reduction unit.

9. In an electric Work utility of the character described, a primary power unit including a motor drive adapted for operation at a predetermined flxed speed and a gear reduction unit operatively associated with said power unit whereby to provide a reduced speed for the ultimate tool or attachment operated by said work utility, said gear reduction unit being interchangeable with other gear reduction units respectively providing different gear ratios, said power unit and its associated gear reduction unit being respectively provided with telescoping parts having coacting means for detachably securing said parts together upon rotation of one of said units relatively to the other.

10. In combination, a main power unit ineluding a predeterminedly fixed speed motor drive, a gear reduction unit including gear-entrained driving and driven shafts, the rear end of said gear reduction unit being adapted for telescopic connection with the fore end of said power unit, and coacting means in the telescoping portions of said units for quick-detachably locking the said units together in assembled relation upon rotation of one of said units relatively to the other, the gear reduction unit being interchangeable as desired with other gear reduction units of respectively different gear ratios.

11. In combination, a main power unit including a predeterminedly fixed speed motor drive, a gear reduction unit including gear-entrained driving and driven shafts, the rear end of said gear reduction unit being teleseopically connected to the fore end of said power unit simultaneously as the driving shaft of the gear reduction unit is coupled to the motor drive of the power unit, and means for removably connecting said units together upon their relative rotation whereby the JAMES C. ROBB. 

